A key is a group of one or more attributes that uniquely identifies a row.

Answer: Option A

Option1: True
- In the relational model, a key is indeed a group of one or more attributes that uniquely identifies a row. This key is used to ensure that each row in a table is unique and can be used to establish relationships between tables.

Option2: False
- This statement is incorrect. A key is essential in a relational database to uniquely identify rows, and it is not optional. Without a key, it would be impossible to distinguish one row from another in a table.

Conclusion:
Based on the explanation provided, the correct option is Option1: True. A key is a group of one or more attributes that uniquely identifies a row in the relational model.